Nystagmus Parameters of Various Rotatory Stimuli

Abstract

For accurate and reliable assessment of vestibular sensitivity a right and left cold caloric test alone is not sufficient. In the combined vestibular test a programmed rotatory testing is added to the cold thermic stimulation. Using an electrically controlled rotating device and photoelectric nystagmography the counterclockwise and clockwise rotation consists of a controlled acceleration (3°/sec²), constant velocity (45°/sec) and sudden stop. Three reactive nystagmus sequences are obtained: (1) threshold and acceleratory response, (2) decreasing perrotatory nystagmus during the constant speed, (3) postrotatory or decelerating nystagmus sequence. The three stimuli are different in strength and create nystagmus sequences in both directions. The two rotations and the cold caloric stimulations yield a total of eight nystagmus sequences. An evaluation of function is greatly facilitated by confirming responses including directional preponderance provided by the four series of tests of various type and strength of stimulations.